Premolar

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Premolar
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The permanent teeth, viewed from the right
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Permanent teeth of right half of lower dental arch, seen from above
Details
Identifiers
Latin dentes premolares
MeSH D001641
TA98 A05.1.03.006
TA2 909
FMA 55637
Anatomical terminology

The premolars, also called premolar teeth, or bicuspids, are transitional teeth located between the canine and molar teeth. In humans, there are two premolars per quadrant in the permanent set of teeth, making eight premolars total in the mouth. [1] [2] [3] They have at least two cusps. Premolars can be considered transitional teeth during chewing, or mastication. They have properties of both the canines, that lay anterior and molars that lay posterior, and so food can be transferred from the canines to the premolars and finally to the molars for grinding, instead of directly from the canines to the molars. [4]

Contents

Human anatomy

The premolars in humans are the maxillary first premolar, maxillary second premolar, mandibular first premolar, and the mandibular second premolar. [1] [3] Premolar teeth by definition are permanent teeth distal to the canines, preceded by deciduous molars. [5]

Morphology

There is always one large buccal cusp, especially so in the mandibular first premolar. The lower second premolar almost always presents with two lingual cusps. [6]

The lower premolars and the upper second premolar usually have one root. The upper first usually has two roots, but can have just one root, notably in Sinodonts, and can sometimes have three roots. [7] [8]

Orthodontics

The four first premolars are the most commonly removed teeth, in 48.8% of cases, when teeth are removed for orthodontic treatment (which is in 45.8% of orthodontic patients). The removal of only the maxillary first premolars is the second likeliest option, in 14.5% of cases. [9]

Other mammals

In primitive placental mammals there are four premolars per quadrant, but the most mesial two (closer to the front of the mouth) have been lost in catarrhines (Old World monkeys and apes, including humans). Paleontologists therefore refer to human premolars as Pm3 and Pm4. [10] [11]

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See also

Related Research Articles

Human tooth calcified whitish structure in humans mouths used to break down food

The human teeth function to mechanically break down items of food by cutting and crushing them in preparation for swallowing and digesting. Humans have four types of teeth: incisors, canines, premolars, and molars, which each have a specific function. The incisors cut the food, the canines tear the food and the molars and premolars crush the food. The roots of teeth are embedded in the maxilla or the mandible and are covered by gums. Teeth are made of multiple tissues of varying density and hardness.

Dentition Development and arrangement of teeth

Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, it is the characteristic arrangement, kind, and number of teeth in a given species at a given age. That is, the number, type, and morpho-physiology of the teeth of an animal.

Canine tooth tooth

In mammalian oral anatomy, the canine teeth, also called cuspids, dog teeth, or fangs, eye teeth, vampire teeth, or vampire fangs, are the relatively long, pointed teeth. They can appear more flattened however, causing them to resemble incisors and leading them to be called incisiform. They developed and are used primarily for firmly holding food in order to tear it apart, and occasionally as weapons. They are often the largest teeth in a mammal's mouth. Individuals of most species that develop them normally have four, two in the upper jaw and two in the lower, separated within each jaw by incisors; humans and dogs are examples. In most species, canines are the anterior-most teeth in the maxillary bone.

Incisor front teeth present in most mammals

Incisors are the front teeth present in most mammals. They are located in the premaxilla above and on the mandible below. Humans have a total of eight. Opossums have 18, whereas armadillos have none.

Malocclusion misalignment or incorrect relation between the teeth of the two dental arches when they approach each other as the jaws close

A malocclusion is a misalignment or incorrect relation between the teeth of the two dental arches when they approach each other as the jaws close. The term was coined by Edward Angle, the "father of modern orthodontics", as a derivative of occlusion. This refers to the manner in which opposing teeth meet.

Maxillary canine

In human dentistry, the maxillary canine is the tooth located laterally from both maxillary lateral incisors of the mouth but mesial from both maxillary first premolars. Both the maxillary and mandibular canines are called the "cornerstone" of the mouth because they are all located three teeth away from the midline, and separate the premolars from the incisors. The location of the canines reflect their dual function as they complement both the premolars and incisors during mastication, commonly known as chewing. Nonetheless, the most common action of the canines is tearing of food. The canines often erupt in the upper gums several millimeters above the gum line. The canine teeth are able to withstand the tremendous lateral pressure caused by chewing. There is a single cusp on canines, and they resemble the prehensile teeth found in carnivorous animals such as the extinct Saber-toothed cat. Though relatively the same, there are some minor differences between the deciduous (baby) maxillary canine and that of the permanent maxillary canine.

Permanent teeth Second set of teeth in diphyodonts

Permanent teeth or adult teeth are the second set of teeth formed in diphyodont mammals. In humans and old world simians, there are thirty-two permanent teeth, consisting of six maxillary and six mandibular molars, four maxillary and four mandibular premolars, two maxillary and two mandibular canines, four maxillary and four mandibular incisors.

Mandibular canine

The mandibular canine is the tooth located distally from both mandibular lateral incisors of the mouth but mesially from both mandibular first premolars. Both the maxillary and mandibular canines are called the "cornerstone" of the mouth because they are all located three teeth away from the midline, and separate the premolars from the incisors. The location of the canines reflect their dual function as they complement both the premolars and incisors during mastication, commonly known as chewing. Nonetheless, the most common action of the canines is tearing of food. The canine teeth are able to withstand the tremendous lateral pressures from chewing. There is a single cusp on canines, and they resemble the prehensile teeth found in carnivorous animals. Though relatively the same, there are some minor differences between the deciduous (baby) mandibular canine and that of the permanent mandibular canine.

Mandibular first premolar

The mandibular first premolar is the tooth located laterally from both the mandibular canines of the mouth but mesial from both mandibular second premolars. The function of this premolar is similar to that of canines in regard to tearing being the principal action during mastication, commonly known as chewing. Mandibular first premolars have two cusps. The one large and sharp is located on the buccal side of the tooth. Since the lingual cusp is small and nonfunctional, the mandibular first premolar resembles a small canine. There are no deciduous (baby) mandibular premolars. Instead, the teeth that precede the permanent mandibular premolars are the deciduous mandibular molars.

FDI World Dental Federation notation is a dental notation widely used by dentists internationally to associate information to a specific tooth.

Dental arch part of the oral cavity of the human being

The dental arches are the two arches of teeth, one on each jaw, that together constitute the dentition. In humans and many other species; the superior dental arch is a little larger than the inferior arch, so that in the normal condition the teeth in the maxilla slightly overlap those of the mandible both in front and at the sides. The way that the jaws, and thus the dental arches, approach each other when the mouth closes, which is called the occlusion, determines the occlusal relationship of opposing teeth, and it is subject to malocclusion if facial or dental development was imperfect.

Tooth eruption Process in which teeth enter the mouth and become visible

Tooth eruption is a process in tooth development in which the teeth enter the mouth and become visible. It is currently believed that the periodontal ligament plays an important role in tooth eruption. The first human teeth to appear, the deciduous (primary) teeth, erupt into the mouth from around 6 months until 2 years of age, in a process known as "teething". These teeth are the only ones in the mouth until a person is about 6 years old creating the primary dentition stage. At that time, the first permanent tooth erupts and begins a time in which there is a combination of primary and permanent teeth, known as the mixed dentition stage, which lasts until the last primary tooth is lost. Then, the remaining permanent teeth erupt into the mouth during the permanent dentition stage.

Dental anatomy

Dental anatomy is a field of anatomy dedicated to the study of human tooth structures. The development, appearance, and classification of teeth fall within its purview. Tooth formation begins before birth, and the teeth's eventual morphology is dictated during this time. Dental anatomy is also a taxonomical science: it is concerned with the naming of teeth and the structures of which they are made, this information serving a practical purpose in dental treatment.

Occlusion, in a dental context, means simply the contact between teeth. More technically, it is the relationship between the maxillary (upper) and mandibular (lower) teeth when they approach each other, as occurs during chewing or at rest.

This is a list of definitions of commonly used terms of location and direction in dentistry. This set of terms provides orientation within the oral cavity, much as anatomical terms of location provide orientation throughout the body.

Dental pertains to the teeth, including dentistry. Topics related to the dentistry, the human mouth and teeth include:

Serial extraction is the planned extraction of certain deciduous teeth and specific permanent teeth in an orderly sequence and predetermined pattern to guide the erupting permanent teeth into a more favorable position.

Human mouth part of human anatomy

In human anatomy, the mouth is the first portion of the alimentary canal that receives food and produces saliva. The oral mucosa is the mucous membrane epithelium lining the inside of the mouth.

Orthodontic indices are one of the tools that are available for orthodontists to grade and assess malocclusion. Orthodontic indices can be useful for an epidemiologist to analyse prevalence and severity of malocclusion in any population.

References

  1. 1 2 Roger Warwick; Peter L. Williams, eds. (1973), Gray's Anatomy (35th ed.), London: Longman, pp. 1218–1220
  2. Weiss, M.L.; Mann, A.E (1985), Human Biology and Behaviour: An anthropological perspective (4th ed.), Boston: Little Brown, pp. 132–135, 198–199, ISBN   978-0-673-39013-4
  3. 1 2 Glanze, W.D.; Anderson, K.N.; Anderson, L.E, eds. (1990), Mosby's Medical, Nursing & Allied Health Dictionary (3rd ed.), St. Louis, Missouri: The C.V. Mosby Co., p. 957, ISBN   978-0-8016-3227-3
  4. Weiss, M.L., & Mann, A.E. (1985), pp.132-134
  5. Warwick, R., & Williams, P.L. (1973), pp.1218-1219.
  6. Warwick, R., & Williams, P.L. (1973), p.1219.
  7. Standring, Susan (2015). Gray's Anatomy E-Book: The Anatomical Basis of Clinical Practice. Elsevier Health Sciences. p. 518. ISBN   9780702068515.
  8. Kimura, Ryosuke; Yamaguchi, Tetsutaro; Takeda, Mayako; Kondo, Osamu; Toma, Takashi; Haneji, Kuniaki; Hanihara, Tsunehiko; Matsukusa, Hirotaka; Kawamura, Shoji; Maki, Koutaro; Osawa, Motoki; Ishida, Hajime; Oota, Hiroki (2009). "A Common Variation in EDAR is a Genetic Determinant of Shovel-Shaped Incisors". The American Journal of Human Genetics. 85 (4): 528–535. doi:10.1016/j.ajhg.2009.09.006. PMC   2756549 . PMID   19804850.
  9. Capelli Júnior, Jonas; Fernandes, Luciana Q. P.; Dardengo, Camila de S.; Capelli Júnior, Jonas; Fernandes, Luciana Q. P.; Dardengo, Camila de S. (2016). "Frequency of orthodontic extraction". Dental Press Journal of Orthodontics. 21 (1): 54–59. doi:10.1590/2177-6709.21.1.054-059.oar. ISSN   2176-9451. PMC   4816586 . PMID   27007762.
  10. Christopher Dean (1994). "Jaws and teeth". In Steve Jones; Robert Martin; David Pilbeam (eds.). The Cambridge Encyclopedia of Human Evolution. Cambridge: Cambridge University Press. pp.  56–59. ISBN   978-0-521-32370-3. Also ISBN   0-521-46786-1 (paperback)
  11. Gentry Steele and Claud Bramblett (1988). The Anatomy and Biology of the Human Skeleton . Texas A&M University Press. p.  82. ISBN   9780890963265.